1. Field of the Invention
The present invention relates to a reproducing apparatus with a built-in optical disk drive.
2. Description of the Related Art
With regard to reproducing apparatuses for disk-shaped storage media such as an optical disk, there are following techniques known to judge whether or not a disk is mounted. That is, Japanese Patent Laid-open No. 2005-302242 (hereafter called “Patent document 1”) discloses a technique to detect a counter-electromotive force of a spindle motor and to determine whether or not an optical disk is mounted based on the amount of change in the counter-electromotive force per unit time. Further, Japanese Utility Model Laid-open No. 62-83256 (hereafter called “Patent document 2”) discloses a technique to determine the presence or absence of a disk based on whether or not data are being read from the disk and based on an electric current flowing through a drive motor for rotating the disk and a signal indicating that a tray on which the disk is mounted is closed. Still further, Japanese Patent Laid-open No. 2003-224988 (hereafter called “Patent document 3”) discloses a technique to utilize a counter-electromotive force found by voltages at both ends of the spindle motor to learn its rotation rate and the direction in which the motor is rotated.
However, in general, since disks vary in weight and shape, there are caused track eccentricity and wobble of the disk surface, and also unevenness in the counter-electromotive force. That is, as described in Patent document 1, when detecting the presence or absence of the disk by the amount of change in the counter-electromotive force per unit time, incorrect detection was very likely to take place. Further, in Patent document 2, one end of the motor for driving the disk to rotate is grounded through a resistor, and the voltage based on the electric current which flows through the motor for driving the disk to rotate is monitored. Therefore, electric power supplied to the motor was consumed by the resistor.